Add delay post SEL clear to purge

By design IPMI sel clearing needs few seconds to clean SEL(s).

Change-Id: Ic40c0a5748f8add373e045ccdcdd8ba47b7972fc
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/ipmi/test_ipmi_sel.robot b/ipmi/test_ipmi_sel.robot
index aefe21b..b8f4a9e 100644
--- a/ipmi/test_ipmi_sel.robot
+++ b/ipmi/test_ipmi_sel.robot
@@ -24,7 +24,9 @@
 Verify Empty SEL
     [Documentation]  Verify empty SEL list.
     [Tags]  Verify_Empty_SEL
+
     Run IPMI Standard Command  sel clear
+    Sleep  5s
 
     ${resp}=  Run IPMI Standard Command  sel list
     Should Contain  ${resp}  SEL has no entries  case_insensitive=True